It is known that, in aircraft, the various electrical cables provided on board are fastened to beams or to frames of the fuselage by means of fastening devices of the type mentioned above. In addition, it is known that, currently, civil transport aircraft are becoming increasingly large, such that their beams and their frames are increasingly wide. It is therefore no longer possible to use the fastening devices currently in use in previous civil transport aircraft for the large modern civil transport aircraft. This is because, on the one hand, these fastening devices are not suitable for being fastened to wide beams or frames and, on the other hand, the cradles currently used for these fastening devices are not wide enough to prevent said cables from rubbing against the wide beams or frames, which leads to electrical insulation faults from wear of the sheaths of these cables and therefore to interference in the operation of the electrical circuit connected to said cables.